A conventional testing apparatus, for example, a probe apparatus comprises a loader unit, which has a conveyance mechanism adapted to convey semiconductor wafers one by one, and also comprises a prober unit adapted to continuously perform electrical tests on the semiconductor wafers. The prober unit has a mount table configured so that semiconductor wafers are transferred one by one between the mount table and the conveyance mechanism, a probe card disposed above the mount table, and a test head adapted to electrically interrupt between the probe card and a tester. The test head is fixed to a rotating shaft through a test head frame and hinges. The test head can turn around the rotating shaft, for example, 180° between a probe apparatus main body and a maintenance area. Recently, the test head has grown in size, so that the weight thereof has reached to 600 kg to 800 kg. To turn such a test head, which is a heavy object, a motor is frequently used. Additionally, the following Patent Document 1 discloses a technique that is substantially the same as the above-described conventional technique.
Patent Document 1: JP-A-9-298224.